The Greeks used fire beacons at the time of the Trojan War, in the twelfth century BC. A bonfire on a mountaintop could be seen from watchtowers twenty miles distant, or in special cases even farther.
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The meaning of the message had, of course, to be prearranged, effectively condensed into a single bit. A binary choice, something or nothing: the fire signal meant something, which, just this once, meant “Troy has fallen.” To transmit this one bit required immense planning, labor watchfulness, and firewood.